Chapter 7. 



MALFORMATIONS AND INJURIES. 



Malformations arising as sports or by malnutrition. Healing 

 of wounds. Injuries due to lightning, frost, etc. Harmful 

 effect of smoke and fog. 



Abnormal development of various parts of plants 

 whether of vegetative or of reproductive organs may be 

 regarded as malformations. Many of these arise as sports 

 or mutations, and may be transmitted to the progeny of 

 the plant. In the case of the vegetative organs such occur- 

 rences as pitcher-shaped leaves have been noted in many 

 instances. Leaves of this type are of no special advantage 

 to the plant, they may indeed be a disadvantage, causing 

 water to collect on the leaf surface and thus increasing the 

 liability to fungal attacks. Among ferns an excessive 

 development of the margin of the frond leads to the 

 development of so-called crested varieties., which being 

 pleasing to some tastes, have been perpetuated by artificial 

 selection. We have no knowledge of the causes of such 

 excessive development of the leaves, nor are we certain 

 of the origin of similar unnatural developments in stems, 

 such as appear in the case of u fasciatipn " (from the Latin 

 fascis, a bundle). This term is applied to the abnormal 

 development of the stem into a broad flattened structure, 

 often caused by the fusion of several stems, or by the union 

 of lateral shoots with the main stem. Superabundance of 



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